CODEWITHSUNDEEP
fortran
ravi
ravi

Reputation:

How to globalize a dummy argument from a function call

How to globalize a dummy argument from a function call?

I have the below code in Fortran 

A(a,b)  // here a and b are the values filling from function call but they are not declared any where
.
.
.
B(a.b) // same variable passing again to this function call also.

here the problem is the values from a and b are not maintaining for second call. it's returning a garbage. Even I tried this using common but its not accepting to globalize dummy arguments. How to do it?

Upvotes: 0

Views: 342

Answers (3)

Zeus
Zeus

Reputation: 1555

Use the SAVE declaration to store the state across invocations of the subroutine or function.

Upvotes: 1

physphun
physphun

Reputation: 396

Dummy variables are by nature, that: dummy arguments. They are simply placeholders, and when a function is called, they get replaced with whatever you passed the function when calling it. lets look at a silly example:

integer function add(x,y)
  integer :: x, y
  add = x + y
end

so now, you can call this function in many ways. lets say you want to add a and b:

integer :: a, b, c

a = 3
b = 4
c = add(a,b)

here, a will take the position of x in the function, and b will take the position of y. c will have the value of 7. you could have just as easily done:

integer :: c

c = add(3,4)

with the same results. as you can see, globalizing dummy arguments is meaningless.

Upvotes: 0

Tim Whitcomb
Tim Whitcomb

Reputation: 10677

You say that "a and b are the values filling from function call but they are not declared anywhere" - even though I'm still trying to figure out exactly what you're trying to do, this statement throws up all sorts of red flags. This is Fortran - you need to declare them (see note).

I'm not clear on what you're trying to accomplish - chances are, though, "globalize" isn't what you want to do - we should be striving to eliminate global variables in our code.

Note: Yes, Fortran (or really, FORTRAN) supports implicit declaration of variables. However, this is a relic from the days of punch cards and dumb terminals. Do Not use implicit typing anywhere - your code should always include implicit none, and you should declare your variables appropriately.

Upvotes: 1

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